Cell-free microRNAs in urine as diagnostic and prognostic biomarkers of bladder cancer

Abstract

Abstract. miRNAs are small, non-coding RNAs that play important roles in various biological processes. The aims of our study were to investigate whether cell-free miRNAs can be measured in urine samples and might be an accurate biomarker of bladder cancer. Datasets of GSE20418 and GSE19717 were used for analysis, and two miRNAs, miR-145 and miR-200a, were selected for study. A total of 207 patients with primary transitional cell carcinoma of the urinary bladder and 144 healthy normal controls were enrolled. Using quantitative PCR, the levels of miR-145 and miR-200a in urine were measured and compared with the clinicopathological features of bladder cancer. According to our experiments, cell-free miRNAs were present in urine and were stable. Assessment of miR-145 levels was able to distinguish bladder cancer patients from non-cancer controls (77.8% sensitivity and 61.1% specificity for NMIBC, AUC 0.729; 84.1 and 61.1% for MIBC, respectively, AUC 0.790) and showed good correlation with grade (p=0.048). In addition, miR-200a was shown to be an independent predictor of NMIBC recurrence by multivariate analysis (OR 0.449, p=0.013). A higher risk of recurrence was observed among patients with a lower miR-200a level compared to patients with higher miR-200a levels (log-rank test, p=0.040). Urinary cell-free miRNAs show promise as noninvasive biomarkers for diagnosis and recurrence of bladder cancer. IntroductionSurveillance strategies for bladder cancer recurrence have historically relied on the diagnostic combination of cystoscopy and urinary cytology. However, the cystoscopic approach is costly, invasive and uncomfortable. Urinary cytology is a preferable technique for the diagnosis of bladder tumors because of its high specificity; however, it has low sensitivity. For these reasons, many new urine-based tests for urinary bladder cancer have been developed, and screens for bladder tumor antigen (BTA), nuclear matrix protein 22 (NMP22), urine fibrin fibrinogen degradation products (FDP), ImmunoCyt and FISH (UroVysion) have all been approved for clinical use (1,2). However, the specificities of these new urine markers are low in comparison with urinary cytology, although they have higher sensitivities. Thus, none of the currently identified urine markers can replace cystoscopy or urinary cytology (3). miRNAs are small, nonprotein-coding RNA regulators involved in numerous biological and developmental processes (4,5). Cumulative evidence suggests that the dysregulation of miRNA plays an important role in many human disorders, including cancer. Approximately 50% of human miRNAs are encoded in genomic regions that are frequently altered in cancer (6-8). Recently, miRNAs have emerged as highly tissue-specific biomarkers with potential clinical applicability, not only as diagnostic markers but also as prognostic predictors for numerous cancers.Numerous recent studies have explored circulating cell-free miRNAs and provided evidence that miRNAs exist in a stable form in various body fluids, such as blood, urine, saliva, and p...

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Beyond circulating microRNA biomarkers: Urinary microRNAs in ovarian and breast cancer

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Extracellular Nucleic Acids and Cancer

“…In contrast to isolated total RNA, the RNA integrity number (RIN value) of which decreased considerably after dilution in water and treatment at 80 C for up to 4 h; this had almost no influence on the stability of cfmiRNA when measured by qPCR [7,86]. Also repetitive freezing and thawing of miRNA samples [87] or of urine samples which were either subjected to seven freeze/thaw cycles or were incubated at room temperature for up to 3 days did not change the amount of miRNA detectable by qPCR [88]. It was also shown that stool derived miRNAs that are either bound to cell membranes or are inside exosomes are rather stable [89].…”